1. Field of the Invention
The present invention relates to a color filter manufacturing method of manufacturing a color filter by discharging inks onto a body to be colored using ink-jet heads having a plurality of ink discharging nozzles and forming colored portions, a color filter, a display device, and an apparatus having the display device.
2. Description of the Related Art
With recent advances in personal computers, especially portable personal computers, demands tend to arise for liquid crystal displays, especially color liquid crystal displays. However, in order to further popularize the use of liquid crystal displays, a reduction in cost must be achieved. Especially, it is required to reduce the cost of a color filter which occupies a large proportion of the total cost. Various methods have been tried to satisfy the required characteristics of color filters while meeting the above requirements. However, any method capable of satisfying all the requirements has not been established. The respective methods will be described below. The first method is a pigment dispersion method. In this method, a pigment-dispersed photosensitive resin layer is formed on a substrate and patterned into a single-color pattern. This process is repeated three times to obtain R, G, and B color filter layers.
The second method is a dyeing method. In the dyeing method, a glass substrate is coated with a water-soluble polymer material as a dyeable material, and the coating is patterned into a desired shape by a photolithography process. The obtained pattern is dipped in a dye bath to obtain a colored pattern. This process is repeated three times to form R, G, and B color filter layers.
The third method is an electrodeposition method. In this method, a transparent electrode is patterned on a substrate, and the resultant structure is dipped in an electrodeposition coating fluid containing a pigment, a resin, an electrolyte, and the like to be colored in the first color by electrodeposition. This process is repeated three times to form R, G, and B color filter layers. Finally, these layers are calcined.
The fourth method is a print method. In this method, a pigment is dispersed in a thermosetting resin, and a print operation is repeated three times to form R, G, and B coatings separately. Colored layers are then formed by thermosetting the resins. In either of the above methods, a protective layer is generally formed on the colored layers.
The point common to these methods is that the same process must be repeated three times to obtain layers colored in three colors, i.e., R, G, and B. This causes an increase in cost. In addition, as the number of processes increases, the yield decreases. In the electrodeposition method, limitations are imposed on pattern shapes which can be formed. For this reason, with the existing techniques, this method is difficult to be applied to TFTs. In the print method, a pattern with a fine pitch is difficult to be formed because of poor resolution and poor evenness.
In order to eliminate these drawbacks, methods of manufacturing color filters by an ink-jet system are disclosed in Japanese Patent Laid-Open Nos. 59-75205, 63-235901, and 1-217320. In these methods, three color inks containing coloring materials of three colors, i.e., R, G, and B, are discharged on a transparent substrate by an ink-jet system, and the respective inks are dried to form colored pixel portions. In such an ink-jet system, R, G, and B pixels can be formed at once, allowing great simplification of the manufacturing process and a great reduction in cost.
In the manufacturing method with the conventional ink-jet system, however, a slight difference between the discharge states of the respective nozzles of the ink-jet head directly influences color filter defects. Conceivable discharge state parameters directly related to color filter defects include the ink landing position, the ink discharging amount, the dot diameter, and the presence/absence of satellite discharging.
For example, the ink discharging amount and the dot diameter are important parameters which influence defects such as a color mixing defect between adjacent pixels and a color irregularity defect caused by a nonuniform amount of ink landed onto each pixel. As for a nozzle having an excessively large or small ink discharging amount or an excessively large or small dot diameter, the discharge state of the nozzle is often different from a designed state for the ink-jet head. Repeating unstable discharging decreases the yield.
The presence of satellite discharging also leads to defects such as a color mixing defect of coloring another pixel, thereby decreasing the yield.
The landing position shift causes a color mixing defect between pixels of a color filter and an excessively bright defect after an ink shifts from pixels. This directly influences the yield.
In the ink-jet method, a large-area color filter can be formed within a short time by using many nozzles for coloring pixels at once. FIG. 20 is a schematic view of an ink-jet head used to color a color filter. In coloring a color filter with many nozzles, nozzles used for coloring are determined by a pixel pattern. The nozzles used are set to make it possible to accurately color pixels aligned at constant pitches while a color filter substrate and the ink-jet head are relatively changed in angle and relatively scanned (FIG. 21). To color a large-area substrate at once, the angles of the color filter substrate and the ink-jet head are preferably small in a direction perpendicular to nozzle alignment and a substrate scanning direction when these angles change (FIGS. 23A and 23B).
In FIG. 21, every third nozzle is used for coloring. As shown in FIG. 22, a different combination (nozzle set) of nozzles can be used by shifting nozzles in use to adjacent ones. The nozzles of the ink-jet head are wasted after long-time use. Therefore, if all three types of nozzle sets can be used, all the head nozzles can be used until they are wasted (normal operation service life).
However, when a given discharging nozzle is defective and cannot color a color filter, a nozzle set including the defective nozzle cannot be used. For this reason, all the head nozzles cannot be used for the full normal operation service life. In other words, the use period of the head is shortened. The ink-jet head must be frequently exchanged, thereby resulting in high cost.
The present invention has been made in consideration of the above situation, and has as its object to provide a color filter manufacturing method capable of efficiently using an ink-jet head.
It is another object of the present invention to provide a color filter manufactured by the manufacturing method, a display device, and an apparatus having the display device.
To solve the above problems and achieve the above objects, a color filter manufacturing method according to the present invention is characterized by the following steps.
There is provided a color filter manufacturing method of discharging an ink from a plurality of ink discharging nozzles onto a plurality of pixels and forming colored portions while an ink-jet head having the plurality of ink discharging nozzles is relatively scanned with respect to a body to be colored on which the pixels, onto which the ink is to be landed, are aligned in advance, comprising the steps of, when some of the plurality of ink discharging nozzles for discharging the ink onto the pixels are defective, stopping discharging of the ink from the defective nozzles, and compensating for a lack of an ink amount in pixels owing to an omission of the defective nozzles, by other nozzles for discharging the ink onto the pixels.
A color filter according to the present invention is characterized by the following arrangement.
There is provided a color filter manufactured by discharging an ink from a plurality of ink discharging nozzles onto a plurality of pixels and forming colored portions while an ink-jet head having the plurality of ink discharging nozzles is relatively scanned with respect to a body to be colored on which the pixels, onto which the ink is to be landed, are aligned in advance, the color filter being manufactured through the step of, when some of the plurality of ink discharging nozzles for discharging the ink onto the pixels are defective, stopping discharging of the ink from the defective nozzles, and the step of compensating for a lack of an ink amount in pixels owing to an omission of the defective nozzles, by other nozzles for discharging the ink onto the pixels.
A display device according to the present invention is characterized by the following arrangement.
There is provided a display device having a color filter manufactured by discharging an ink from a plurality of ink discharging nozzles onto a plurality of pixels and forming colored portions while an ink-jet head having the plurality of ink discharging nozzles is relatively scanned with respect to a body to be colored on which the pixels, onto which the ink is to be landed, are aligned in advance, integrally comprising a color filter being manufactured through the step of, when some of the plurality of ink discharging nozzles for discharging the ink onto the pixels are defective, stopping discharging of the ink from the defective nozzles, and the step of compensating for a lack of an ink amount in pixels owing to an omission of the defective nozzles, by other nozzles for discharging the ink onto the pixels, and light amount changing means for changing a light amount.
An apparatus having a display device according to the present invention is characterized by the following arrangement.
There is provided an apparatus having a display device with a color filter manufactured by discharging an ink from a plurality of ink discharging nozzles onto a plurality of pixels and forming colored portions while an ink-jet head having the plurality of ink discharging nozzles is relatively scanned with respect to a body to be colored on which the pixels, onto which the ink is to be landed, are aligned in advance, comprising: a display device integrally comprising a color filter being manufactured through the step of, when some of the plurality of ink discharging nozzles for discharging the ink onto the pixels are defective, stopping discharging of the ink from the defective nozzles, and the step of compensating for a lack of an ink amount in pixels owing to an omission of the defective nozzles, by other nozzles for discharging the ink onto the pixels, and light amount changing means for changing a light amount; and image signal supply means for supplying an image signal to the display device.
Other objects and advantages besides those discussed above shall be apparent to those skilled in the art from the description of a preferred embodiment of the invention which follows. In the description, reference is made to accompanying drawings, which form a part hereof, and which illustrate an example of the invention. Such example, however, is not exhaustive of the various embodiments of the invention, and therefore reference is made to the claims which follow the description for determining the scope of the invention.